im looking all over the internet for some script (UIpanel) for after effects that allows me to:
select all keyframes from all layers in the current frame (on the timeline)
like this: http://imgur.com/BNY7QLB

the idea is to select keys on all layers, colapsed or not (or has an option to choose that).
the most close to a "move master keyframe" concept.

other thing great would be have the hability to move a keyframe or group of keyframes forward or backward (in timeline) with a button (one button for 1 frame, and another for specefic ammount would be amazing!), so you dont have to select and move it with the mouse.

maybe something that use as reference the currentframe (the current time indicator) to help the selections (im just dropping ideas here)

any flash, toon boom, or anime studio animator understand what im talking about here. in toon boom for example you have a lott of tools, buttons and hotkeys to play arround with the keyframes in the timline. i understand that after effect doenst because originally isnt a soft for animation. but if we animate directly on after thanks to duik (and DUgr), we need a third Du** to work with the timeline keyframes, and with that we have ALL the field covered

im making a cut out animation with duik rig, and i have a lot of keyframes in all the layers of the character. and when i need to adjust the keyframes timing i have to select all the keyframes in all the layers in the current frame to move it, and with all the rig i have more than 30 layers! it has to be a easy way.

I'm pretty new to character animating in After Effects myself, but I'm finding the 'Paste Multiple Keyframes' plugin pretty useful. It doesn't do all the things you outline, but you can select multiple keyframes on different layers, and paste them to where the playhead is. It's similar to 'Alt-Drag' in Flash.
It would be great if there were a better keyframing tools though!

In the "animation" panel of Duik, there are buttons to copy and paste keyframes too, able to copy and paste multiple keys on multiple layers
There are a few options for this tool in the settings panel, to choose how keyframes are pasted.

thanks for the observations. i already know about both. but what im raising here its something more deep.
any good animation needs a lot of work and a lot of keyframe-timings move arround manipulations. its not only a matter of copy paste keys.